1. Field of the Invention
This invention relates generally to signs and more particularly to an improved system for mounting individual letters particularly those made of synthetic resin and mounted on a synthetic resin support surface.
2. Description of the Prior Art
There are many systems presently available for mounting letters on a vertical support surface for the purpose of forming a sign. One example of the prior art is shown in U.S. Pat. No. 3,225,477 granted on Dec. 28, 1965 to L. N. Edwards. In this patent the interchangeable letters are provided with brackets secured to the rear faces thereof. The brackets define recesses that can readily accommodate portions of resilient clips. Tangs formed on the rear faces of the brackets extend into openings or recesses in the feet of the resilient clips so that when the resilient clips are inserted into the recesses defined by the brackets on the rear faces of the letters, the tangs on the brackets engage the recesses or openings in the feet of the resilient clips and thereby prevent accidental separation of the clips from the letters. It will be evident from a review of this patent that it is difficult to mount the letters since the brackets are on the rear face thereof and are not visible. Accordingly, in mounting the letters the operator is working in the "blind." This presents considerable difficulty and serves to increase the cost of installation.
U.S. Pat. No. 2,880,537, U.S. Pat. No. 2,916,839 and U.S. Pat. No. 3,142,124 all represent another form of prior art devices that are used in cooperation with individual letters for forming a sign. All of the last three mentioned patents relate to clip-on letters that require some form of groove, aperture or rail for their installation. It will be appreciated that the construction taught by the last three mentioned patents requires a support surface that is relatively expensive to form and which also interferes with rain washing.
Still another form of prior art is shown in U.S. Pat. No. 2,496,747 which utilizes suction cups for retaining individual letters on a vertical surface such as glass. It will be evident that unless the glass is perfectly clean and perfectly flat the suction cups will tend to release the letters and thereby permit them to fall. In addition, atmospheric changes will also adversely affect the continuous operability of the suction cups.